An internal combustion engine includes an engine block defining a plurality of cylinders having bores, and pistons that reciprocate within the cylinder bores to generate mechanical power. A cylinder head sits on top of the cylinder bores to form combustion chambers, in which fuel and air are injected. Injectors of the internal combustion engines are designed to proportionately distribute mechanical power between the plurality of cylinders. However, the proper distribution of mechanical power may be disrupted by a number of issues, including faulty mechanical construction, inevitable wear of the mechanical components, and ineffective combustion controls. This imbalance can cause numerous undesirable effects including reduced engine performance, unbalanced torsional forces on the crankshaft, excessive stresses on engine components, and increased fuel consumption and emissions.
The conventional method of engine balancing involves taking direct pressure measurements at a bottom deck of the cylinder head. The pressure measurements are analyzed and compared to determine which cylinders are firing high or low, relative to the average pressure of the cylinders. This method has some drawbacks due to the fact that the conventional pressure sensor requires holes to be drilled through the cylinder head to expose the sensor to the pressurize inside the cylinder bore. The holes compromise the strength and the durability of the cylinder, and the location at the bottom deck experiences high temperatures thus potentially causing errant readings and necessitating bulky coolant components.
One attempt to improve the conventional method of sensing pressure in a combustion chamber is disclosed in U.S. Pat. No. 4,620,093 of Barkhoudarian et al. that published on Oct. 28, 1986 (“the '093 patent”). In particular, the '093 patent discloses a non-intrusive optical pressure sensor for measuring the pressure of a rocket engine. The pressure sensor is composed of a pressure deflectable diaphragm in communication with the subject container and which includes a diffraction grating on one of its surface, means for directing a laser to strike the optical grating, and a photo-position detector for generating pressure signals responsive to the changes in position of the diffraction grate.
Even though this method of sensing pressure may provide some improvement because it does not require exposure to the combustion chamber, it is still less than optimal. Generally, the pressure sensor of '093 is specifically designed for space flight, which experiences different conditions than the typical vehicular combustion chamber. The addition of a deflectable diaphragm to a vehicular cylinder would require substantial reconstruction, adding costs and inherently reducing strength of the cylinder. The pressure sensor of '093 also requires an undesirable wall thickness to accommodate the complex pathway of the laser.
The laser system of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.